Talk:Screw

Suggestions

• Kudos, what a great page! I'm not sure if tensile strength ratings and failures would be suitable here. Just a suggestion --Artyboats 23:16, 19 April 2007 (UTC)

• The american quarter is not really appropriate for en.wikipedia. An english penny would be better

• It would be good to include information on 5-lobe/point Torx screws, ie. "Tamper-resistant TORX PLUS". It's not straightforward to Google up information on these. User5910 19:34, 11 June 2007 (UTC)

• A table of standard gage sizes? There's one for metric but not UNC/UNF.

• Under the subheading,"Shapes of screw head," the pan head is described with a having a chamfer; actually that would describe a binding head. Pan heads are virtually flat on the bottom of the head.

They are chamfered on the top, however. -- Sakurambo 桜ん坊 17:16, 29 July 2007 (UTC)

Cones and cylinders

Page says that screws are threaded cones and bolts threaded cylinders, but machine screws (like the computer screw image) are threaded cylinders. 192.150.5.150 17:57, 7 September 2006 (UTC)

Motion and Dual screws

I'm not an native English speaker, so I might be off with this one (i.e. you may be calling these something else, not screws), but I'm an engineer so I couldn't avoid noticing there are a few pieces of information missing from this article:

1. There is no mention about "motion screws", as we call them over here, screws which are designed for movement rather than blockage -- e.g. the one in a manual press;

These are called lead screws.

2. There is no mention of dual screws, both left-handed and right-handed -- these are used for applications where there is no room for the screw head, such as for mill "teeth". I don't know what the proper term is, but the idea is that both the mill and its "teeth" are precision pieces, pretty expensive to build, so its "teeth" are made separately out of tougher materials in order to allow changing them. Since there is no room on either side of the tooth for neither the screw head nor the nut, they're fastened to the mill by the means of a special, dual screw, which simply screws in both the mill and the tooth with no end visible on either side. And they do get fastened exactly because half of the screw is left-handed and half is right-handed, so turning it in one direction screws/unscrews it into/out of both pieces.

-- Gutza 0:34 14 Jul 2003 (UTC)

Is there a difference between lead screws and worm gears?

Is there a difference between lead screws and worm gears ? Neither one are "fasteners", but both (along with Archimedes's screw) are included in the idea of the simple machine screw

My understanding is that a lead screw is meant to turn the rotary motion of the lead screw into the linear translation of the block on it, whereas a worm gear turns the rotary motion of the worm (the long shaft with grooves) into the rotary motion of the worm gear (probably a spur gear). I don't know if you can back drive a lead screw or not, but I know you generally cannot back drive a worm gear. Dachande 18:01, 24 July 2007 (UTC)

Screws can be taken apart and replaced

Screws are more versatile than nails: they can be taken apart and replaced.

I do not understand what is intended by that sentence. I do know that it is incorrect. I have never seen a screw successfully taken apart and reassembled. I suspect a pronoun reference problem. --KQ 09:54 Aug 18, 2002 (PDT)

What that means is this: take 2 pieces of wood held together by nails, and take out the nails. The nail holes can't be reused to put them back together again. Do the same with screws, and (with decent wood, wel-drilled holes etc) the screws can be replaced. -- Tarquin

Ok, thanks. --KQ

Phillips screws

Phillips screws were invented in the 1930s by Henry Phillips, and the patent has long since expired. These are "cross heads", so I fail to see why these have been listed separately. Eclecticology 21:24 Aug 18, 2002 (PDT)

The main reasons for mentioning Phillips screws are

1. Everyone has heard of them and despite the patent, which didn't expire, but was taken away from Phillips, they are still manufactured according to his design;
2. The design was intended to cam out, which makes them totally inappropriate for most of the uses to which they are put.

I will combine the cross-head and Phillips entries under Phillips.

Ortolan88 21:39 Aug 18, 2002 (PDT) Sorry, I hadn't realized it had been taken away, but even without that the basic design would have fallen into the public domain.
I think that the concept of "cam out" may need to be explained somewhere. Eclecticology

Article says "ride out, or cam out, under strain". Everyone who has ever tried to use a Phillips will recognize what is meant, but add wording if you can improve. Ortolan88

Okay, why were Phillips head screws "intentionally made so the driver will ride out, or cam out, under strain?" Slrubenstein

To hazard a guess, so that the power screwdriver doesn't rip the head to shreds / sit there immobile straining the motor when the screw gets as far in as it will go. --Brion

Uh, weren't these screws in use before power 'drivers?

According to the article, they were designed specifically for "use with mechanical screwing machines". Maybe not the 'lectric we know and love today, but it sounds like something that won't necessarily know when to stop turning. --Brion

I haven't looked at this in depth, but I can see another advantage to having the screwdriver ride out. It could function on the same principle as a torque wrench to prevent any damage caused by tightening screws too much. Eclecticology 01:49 Aug 25, 2002 (PDT)

You are right, according to this article on the web: http://www.americanheritage.com/it/2001/02/objlessons.shtml --user:Heron

This link no longer works --Bruce: user

There used to be an article on the Philips web site explaining why the thing was designed to cam out. It had to do with not overtightening in automotive bodywork applications. But this document : (http://scholar.lib.vt.edu/theses/available/etd-42698-205111/unrestricted/chapter_2.pdf) suggests the matteris much more complex. -- Brunnian 02:16, 30 April 2007 (UTC)

The Phillips recess is described in the book 'One Good Turn', which has a Wikipedia article, although I haven't checked it. The book is a good read though.

Threaded Fastener

Isn't a "Threaded Fastener" a category of screw? If so it should not be in a section by itself. Wake 02:15, 11 Nov 2003 (UTC)

Bolt

Bolt seems to redirect here. This could perhaps be replaced with a disambiguation page mentioning lightning bolts, crossbow bolts (ie quarrels, and quite especially the type of locking device. --blades 00:41, May 16, 2004 (UTC)

You are absolutely right. I have created a new disambiguation page. -- Wapcaplet 05:13, 16 May 2004 (UTC)

Threaded Fasteners

The arrangement of the page makes it difficult to define the types and uses of bolts (Hex-head, Square-head, Flange, Carriage, Plow, Stove, U-bolt, Internal drive(hex, torx) and nuts (Hex, Square, Locking (all-metal, inserted), Slotted, Castle). I would propose renaming the page Threaded_fasteners and organizing it as similar to below.

Subject: Threaded fastener

Table of contents:

1 Mechanical Analysis

2 Tensile Strength

3 Screws
3.1 Types of Screws
3.2 Shapes of Screw Head
3.3 Types of Screw Drive
3.4 Tools Used

4 Bolts
4.1 Types of Bolts
4.2 Shapes of Bolt Head
4.3 Types of Bolt Drive
4.4 Tools Used

5 Nuts
5.1 Types of Nuts
5.2 Tools Used

6 Threaded Fastener Measurements
6.1 Metric
6.2 SAE
6.3 Other
— dmc 12 Aug 2004

Washers

As one of the ancient parents of this article (and former hardware-store clerk and construction worker), I concur that this organization would be much better and would accommodate all the accretions in an efficient and useful form. I wonder if there shouldn't also be a section on washers:

x Washers

x.1 Flat washers

x.2 Lock washers

x.2.1 spring-loaded lock washers

x.2.2 star washers

Washers are a definite part of the nut-bolt system, essential in spreading the load, preventing damage to the underlying surface, and, in the case of lock washers, holding it all together. Ortolan88 16:52, 11 Aug 2004 (UTC)

Washers are a good idea. It's been a week and no other input so I'll probably move the page in the next couple of days. Unless you want to. Never did find my old password. I'll go ahead and leave this page as it is until the other looks presentable. Someone with more knowledge than I and better composition skills will need to look it over. — dmc, 19 Aug 2004

I'll take a look at it after you move it. Good on you for taking this on. Ortolan88 17:15, 19 Aug 2004 (UTC)

I started a washer page and a belleville washer page. Am planning to merge the belleville into the washer page as I work more on it.

Bolted joint

I think there is enough information (much of it not already in screw) to start a new page on bolted joints. It could concentrate on the joint design and cover;

• capscrews and machine screw types, ratings and markings
• thread strength and calculations
• nut and washer selection
• pre-load design
• locking mechanisms
• Torquing tools, calculations and measuring devices
• Torque indicating washers for structural applications

Pud 23:16, 21 Aug 2004 (UTC)

I'm glad I checked the discussion before moving the page. Are you suggestiong leaving the Screw page as it is and adding another page for Nuts & Bolts? Sounds appropriate and more thorough than what I was thinking. I still think, however, the Screw should be the page for the Screw as a Simple_machine and that the Screw as a threaded fastener should be elsewhere. Maybe a Threaded_fastener page could still be created describing the types and general uses of threaded fasteners with links to the various kinds. Maybe the naming conventions could be stabilized somewhat too. Nuts exist under Nut_(hardware), Washers under Washer_(mechanical), and Screw under just plain Screw. —Dmc6006 19:33, 22 Aug 2004 (UTC)

With a good set of cross-references, any organization will work, but Threaded fastener seems to include all the other categories. Ortolan88 20:21, 22 Aug 2004 (UTC)

I agree that using the threaded fastener topic would be better since it is usually used as the encompassing term for both screws and bolts. The organization proposed by dmc above seems good to me as well. --Lloydd 06:32, 22 Dec 2004 (UTC)

I think the Screw page is very good and wouldn't want to mess it up. It has a very nice combination of brevity, clarity and range of detail. And there is still room for growth without the page becoming unwieldy.

• (User:Dmc6006) Yes, I would leave the Screw page as it is. I was thinking more engineering as opposed to hardware (Bolted_joint vs. Nuts & Bolts)
• (User:Dmc6006) ...simple machine vs. threaded fastener... I think two pages, one for fastener and one for machine is viable. Screw_(simple machine) could cover worm gears, linear actuators, augars, etc...
• (User:Ortolan88) ...cross-references... , we could use a hardware category.

Pud 00:36, 23 Aug 2004 (UTC)

I agree that the article is good one for the hardware screw and expanding it to include other fasteners could reduce its clarity. The screw page started life as a stub for the simple machine. It seems to have evolved rather rapidly into an article about the screw as a threaded fastener. Screw is used interchangeably for both meanings on this page and I don't know a good way to clear up the confusion. Also, the bolt is only briefly mentioned and much of the information applies to both bolts and screws. While both bolts and screws are applications of the screw design, they have different lineages. Anyway, that's my theory for renaming the page threaded fastener, expanding it to include all threaded fasteners, and returning this page to reference only the basic screw. —Dmc6006 14:51, 23 Aug 2004 (UTC)

Threadforms

I was under the impression that BSW (British Standard Whitworth) and BSF (British Standard Fine) were only related in that they both hail from Britain. Martin Rudat(T|@|C) 13:57, 17 February 2006 (UTC)

I think that it would be useful to mention that pipe threads are specified with a taper, so that it is possible to have the clearance between the male and female thread needed to easily screw pipe together, whilst also allowing a seal without needing to use sealant. Martin Rudat(T|@|C) 13:57, 17 February 2006 (UTC)

From what I've read in a copy of the "Engineer's Handbook" (an old edition, about as thick as a telephone directory), threadforms could easily be expanded upon to justify a seprate article. Martin Rudat(T|@|C) 13:57, 17 February 2006 (UTC)

Duplicate External Link

Lara Specialty Tools has a more extensive guide to 24 screw head types.

Removed from body of text.

Pitch vs Depth

"The diameter of a metric screw is the outer diameter of the thread. The tapped hole (or nut) into which the screw fits, has an internal diameter which is the size of the screw minus the pitch of the thread. Thus, an M6 screw, which has a pitch of 1 mm, is made by threading a 6 mm shaft, and the nut or threaded hole is made by tapping threads in a 5 mm hole."

This doesn't make sense to me - isn't the pitch measured across the length of a bolt (peak to peak like a wavelength)? Shouldn't it be which is the size of the screw minus the depth of the thread. Thus, an M6 screw, which has a depth of 1 mm...?

Strictly speaking you are right, but the approximate equivalance of pitch and thread depth comes from the 60 deg angle of ISO metric and UNF/C threads (ignoring the finer points about the precise tops and bottoms of the threads). --Pcrawford 11:22, 25 November 2006 (UTC).

Mechanics of use

I spent some time researching for mention of this subject. User:Rhodescus contains the references I managed to find on the web. I'm unsure how to list those references for this article in any useful way.

The rational for the entry, the proper use of screws, is deemed an important subject amongst tradesmen, technicians and other types who routinely service and maintain equipment which utilize screws (including computers!). The main principle behind the use of screws is alignment of the screw. I don't think enough attention was paid to this principle, in this article.

Also, I think my edit invalidate the statement in the second paragraph, "Screws can normally be removed and reinserted without reducing their effectiveness." A properly trained tradesman or technician who has been shown how to use screws can repeatedly remove or reinsert screws without reducing their effectiveness. Of course, that's harder to verify (but eminently true,) and depends on both the material and the screw (also true but I can't verify it.)

But is verifiable, and well known among tradesmen and technicians, that there is only one way to effectively reuse a screw in the same hole, and that the effective method is apparently counter-intuitive to most. I hope this is a useful contribution to this article, and I hope someone can show me how my references can be cited for the article, as they verify my edit.

Rhodescus 07:17, 24 September 2006 (UTC)

Why do we still get slotted screws?

This design seems to be akin to the square wheel to me? However I'm no engineer, so would really love to know an experts opinion!

Probably a combination of tradition and cheapness. Philips/Pozidrive are much more convenient for power drivers, and work very well as long as you use the correct matching tool! --Pcrawford 11:26, 25 November 2006 (UTC)

One advantage is non-magnetic slotted screws can be held flush with a special screwdriver.

- I believe the reason we have slotted screws is that everyone has a slotted screwdriver. Of all the fastener recesses, slotted is by far the worst in almost any technical performance respect - camout, stripping, off-axis drive capability, torque capacity, etc. It just sucks. The only good feature other than one that just mentioned is that you can sometimes turn a slotted fastener with a bit that doesn't quite fit, or with something that isn't a bit at all, like a coin. Many of the modern fastener recesses are quite unforgiving if you lack the exact bit for the specific recess.

I don't think cost is that much of a factor, especially for fastener recess types whose patents have expired. It's all about convenience.

I'm not sure what the comment about 'flush with a special screwdriver' means. —The preceding unsigned comment was added by 68.160.170.31 (talk) 10:34, August 23, 2007 (UTC)

Screws infbox

I have created {{Screws}} infbox to replace the large captioned image. Please comment and improve. Also, this might be a good time to create articles on other screw drive types. Shinhan 20:37, 27 November 2006 (UTC)

Wheel stud

A new stub article wheel stud has appeared. I wondered whether it shouldn't be redirect here. What do you think? --Edcolins 13:57, 17 December 2006 (UTC)

What is a JCBC Screw?

I can't find any information on what "JCBC" stands for in this context, though Google turns up a number of places selling them. Anybody know about these? —Długosz 22:02, 27 December 2006 (UTC)

http://www.titanhardware.com/pdf/CS_SCREWS.pdf lists other forms in the 'JC' series - I always understood that the JC referred to 'joint connector' -- Brunnian 02:02, 30 April 2007 (UTC)

Do we need a security/tamper-proof screw page?

There are many screws designed to be "Tamper-proof". Do we need to make a page for it? --Af648 02:33, 9 January 2007 (UTC)

Capscrew photo

I added a capscrew photo because I couldn't find out here in Wiki what a capscrew is. I found out by going to the hardware store. I thought I'd save the next person the trip. --SueHay 20:33, 13 March 2007 (UTC)

captive screws

There are articles that refer to captive screws, like Mac Pro, but I don't believe Wikipedia ever actually explains what captive screws are. Herorev 05:34, 17 April 2007 (UTC)

- Captive screws are designed not to fall out once installed. —The preceding unsigned comment was added by 68.160.170.31 (talk) 10:36, August 23, 2007 (UTC)

Bolts versus screws

I've always be told that the difference between a screw and a bolt is that a bolt is used with a nut whereas a screw isn't. In this article it says that some screws are used with nuts. 'Cap screws may, or may not be used with nuts.'

The definition I've found for bolts is 'a long metal pin with a head that screws into a nut, used to fasten things together'[1] and the one for a screw is 'a thin, sharp-pointed metal pin with a raised spiral thread running around it and a slotted head, used to join things together by being rotated in under pressure.'[2].--Jcvamp 20:34, 27 May 2007 (UTC)

The treatment of bolts on Wikipedia is inconsistent and unsatisfactory at present. If you try to get info on bolts on Wikipedia you are led from Bolt diasmbig page to this article which doesn't mention bolts at first, then says "A screw, by definition, is not a bolt" and directs you to this: "See also: Bolt manufacturing process" which isn't about bolts per se, there isn't an article on them. Then later the articles starts to treat bolts and screws together. It's illogical, Captain! Rexparry sydney 04:12, 31 July 2007 (UTC)

3-2 screws

I have a 3-2x5mm machine screw (for circuit boards). What kind of sizing is 3-2? I don't see any notation like it under ISO metric screw threads, Whitworth, BA, or Unified Thread Standard.

Tri-wing?

Actually it's widely used in aviation. I believe it was originated from Lockheed aircraft L-1011 TriStar era, also used on other aircraft like MD-11 (welp, are those tri-engined aircrafts also mean tri-shaped fastener? :D).

The idea was that it would cam out easily when tightening, to prevent overtightening, but grip hard when loosening. So it was not intended for the tamper-proof purpose, and as for tamper-proof purpose, I think it was choosen because of the screw can be made very small sized than other type (gameboy screw? =D).

In the real aviation use, these screws are very nasty, as the flute is shallower than positive drive it can get damaged easily if one doesn't apply enough pressure or maintain a straight angle when loosening. Comparable to Airbus' Torq-Set but slightly different reason, the Torq-Set's flute is set as if the tightening grip is more than loosening grip, so one can easily overtorque it and became very very difficult to remove as the loosening grip is lower, it will just slip/cam out, damaging the screwhead in the further process. The best method is by always using a torque gauge when tightening a screw (as in the maintenance rule) but in the real world, that's very tedious work limiting it only used in the critical parts of the aircraft.

221.126.136.80 13:51, 27 June 2007 (UTC) Katt

Great info, there is a page about Tri-Wing screws, maybe you would like to contribute to it but you need a source/reference Af648 07:56, 23 July 2007 (UTC)

Misc. comments

Tri-Wing, Torq-Set, and Pozidriv are all designs and trademarks of the Phillips Screw Company: http://www.phillips-screw.com/ . Another recent product of theirs is Mor-Torq. Yes, these are all primarily aviation or aerospace fasteners, but are sometimes used as security screws because the recesses are relatively uncommon. However, given that you can now buy comprehensive sets of 'security' bits anywhere, including Sears, I would not want to use them as security fasteners.

Because they are aerospace fasteners, they have design objectives for specific applications. For instance, the torque to remove a fastener often far exceeds that to install it because the fastener becomes frozen. Hence the fastener recess may be designed so as to withstand the larger removal torque.

Phillips also developed the ACR (Anti Camout Ridges) on the Phillips recess, which helps to hold the bit is the screw. Note that by design, Phillips will camount under excessive torque.

The list of fastener recesses is incmplete and out of date. For example, I don't see Torx-Plus listed. Like Torx, it is a product of Camcar Textron, but the patent on Torx-Plus is still running, which has limited its adoption. I also don't see the Recex/Quadrex/square-Phillips combo recess. There are many other on the market these days that are not listed here, e.g. ASSY, XZN (commmonly called triple-square to advoid trademark issues) and found in some cars. There ia also an interesting variant on the familiar hex (Allen, a trademark) recess.

The information about Robertson being different from 'American' square drive in terms of its taper is totally false. This shows up from time to time in woodworking magazines, and I looked into it by speaking by phone with James Ray, owner of McFeely's Square Drive Screws in Virginia (www.mcfeelys.com). He told me that the reason the screws are called square drive in the US is the trademark issue and licensing fees over the use of the name many years ago. Robertson is said to be viewed as something of a Thomas Edison in Canada, and I get the impression from several letters to the editor that I have read over the years is that the Canadians and others have used this issue to express their anti-Americanism. I saw one such letter in a British woodworking magazine by a man who had lived in Canada for a period. He was extolling the virtues of the screw, and then went on a rant about how they are called square drive in the US because Americans don't want to acknowledge anything that didn't come from the US.

The Robertson name is used here and there in the US for either the fasteners or the bits that drive them, though square or square drive is more common because of the history of the name mentioned above. —The preceding unsigned comment was added by 68.160.185.160 (talk) 14:03:26, August 19, 2007 (UTC)

For those interested in the more technical aspects of fasteners, check out the fastener trade bimonthlies 'American Fastener Journal' and 'Fastener Technology International'. Also, check out the publications of the International Fastener Institute (IFI). —The preceding unsigned comment was added by 68.160.170.31 (talk) 10:40, August 23, 2007 (UTC)